///
// Copyright 2013,2016 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: GPL-3.0-or-later
//

#include <uhd/transport/nirio/rpc/rpc_client.hpp>
#include <uhdlib/utils/narrow.hpp>
#include <boost/asio/error.hpp>
#include <boost/format.hpp>
#include <boost/version.hpp>


#define CHAIN_BLOCKING_XFER(func, exp, status)                                    \
    if (status) {                                                                 \
        status = (static_cast<size_t>((func)) == exp);                            \
    } else {                                                                      \
        UHD_LOGGER_DEBUG("NIRIO") << "rpc_client operation skipped: " #func "\n"; \
    }

namespace uhd { namespace usrprio_rpc {

using boost::asio::ip::tcp;

rpc_client::rpc_client(const std::string& server,
    const std::string& port,
    uint32_t process_id,
    uint32_t host_id)
    : _socket(_io_context), _hshake_args_server()
{
    // Fill in handshake info
    _hshake_args_client.version             = CURRENT_VERSION;
    _hshake_args_client.oldest_comp_version = OLDEST_COMPATIBLE_VERSION;
    _hshake_args_client.client_id           = build_client_id(host_id, process_id);
    _hshake_args_client.boost_archive_version =
        boost_serialization_archive_utils::get_version();

    try {
        // Synchronous resolve + connect
        tcp::resolver resolver(_io_context);
        // All special flags disabled. Especially the following:
        //- address_configured: Only return addresses if a non-loopback address is
        // configured for the system.
        //- numeric_host: No name resolution should be attempted for host
        //- numeric_service: No name resolution should be attempted for service
        auto endpoints = resolver.resolve(server, port, tcp::resolver::passive);
        boost::asio::connect(_socket, endpoints);

        UHD_LOGGER_TRACE("NIRIO") << "rpc_client connected to server.";

        try {
            // Perform handshake
            bool status = true;
            CHAIN_BLOCKING_XFER(boost::asio::write(_socket,
                                    boost::asio::buffer(&_hshake_args_client,
                                        sizeof(_hshake_args_client))),
                sizeof(_hshake_args_client),
                status);
            CHAIN_BLOCKING_XFER(boost::asio::read(_socket,
                                    boost::asio::buffer(&_hshake_args_server,
                                        sizeof(_hshake_args_server))),
                sizeof(_hshake_args_server),
                status);

            _request.header.client_id = _hshake_args_server.client_id;

            if (_hshake_args_server.version >= _hshake_args_client.oldest_comp_version
                && _hshake_args_client.version >= _hshake_args_server.oldest_comp_version
                && status) {
                UHD_LOGGER_TRACE("NIRIO") << "rpc_client bound to server.";
                _wait_for_next_response_header();

                // Spawn a thread for the io_context callback handler. This thread will
                // run until rpc_client is destroyed.
                _io_context_thread.reset(new boost::thread(
                    boost::bind(&boost::asio::io_context::run, &_io_context)));
            } else {
                UHD_LOGGER_DEBUG("NIRIO") << "rpc_client handshake failed.";
                _exec_err.assign(boost::asio::error::connection_refused,
                    boost::asio::error::get_system_category());
            }
            UHD_LOGGER_TRACE("NIRIO")
                << boost::format("rpc_client archive = %d, rpc_server archive = %d\n.")
                       % _hshake_args_client.boost_archive_version
                       % _hshake_args_server.boost_archive_version;
        } catch (boost::exception&) {
            UHD_LOGGER_DEBUG("NIRIO") << "rpc_client handshake aborted.";
            _exec_err.assign(boost::asio::error::connection_refused,
                boost::asio::error::get_system_category());
        }
    } catch (boost::exception&) {
        UHD_LOGGER_TRACE("NIRIO") << "rpc_client connection request cancelled/aborted.";
        _exec_err.assign(boost::asio::error::connection_aborted,
            boost::asio::error::get_system_category());
    }
}

rpc_client::~rpc_client()
{
    _stop_io_context();
}

const boost::system::error_code& rpc_client::call(func_id_t func_id,
    const func_args_writer_t& in_args,
    func_args_reader_t& out_args,
    boost::posix_time::milliseconds timeout)
{
    std::unique_lock<std::mutex> lock(_mutex);

    if (_io_context_thread.get()) {
        _request.header.func_id = func_id;
        in_args.store(_request.data);
        _request.header.func_args_size = uhd::narrow_cast<uint32_t>(_request.data.size());

        _exec_err.clear();

        // Send function call header and args
        bool status = true;
        try {
            CHAIN_BLOCKING_XFER(
                boost::asio::write(_socket,
                    boost::asio::buffer(&_request.header, sizeof(_request.header))),
                sizeof(_request.header),
                status);
            if (not _request.data.empty()) {
                CHAIN_BLOCKING_XFER(boost::asio::write(_socket,
                                        boost::asio::buffer(&(*_request.data.begin()),
                                            _request.data.size())),
                    _request.data.size(),
                    status);
            }
        } catch (boost::exception&) {
            status = false;
        }

        // Wait for response using condition variable
        if (status) {
            if (!_exec_gate.timed_wait(lock, timeout)) {
                UHD_LOGGER_DEBUG("NIRIO") << "rpc_client function timed out.";
                _exec_err.assign(boost::asio::error::timed_out,
                    boost::asio::error::get_system_category());
            }
        } else {
            UHD_LOGGER_DEBUG("NIRIO") << "rpc_client connection dropped.";
            _exec_err.assign(boost::asio::error::connection_aborted,
                boost::asio::error::get_system_category());
            _stop_io_context();
        }

        // Verify that we are talking to the correct endpoint
        if ((_request.header.client_id != _response.header.client_id) && !_exec_err) {
            UHD_LOGGER_DEBUG("NIRIO") << "rpc_client confused about who its talking to.";
            _exec_err.assign(boost::asio::error::operation_aborted,
                boost::asio::error::get_system_category());
        }

        if (!_exec_err)
            out_args.load(_response.data);
    }

    return _exec_err;
}

void rpc_client::_handle_response_hdr(
    const boost::system::error_code& err, size_t transferred, size_t expected)
{
    std::lock_guard<std::mutex> lock(_mutex);
    _exec_err = err;
    if (!_exec_err && (transferred == expected)) {
        // Response header received. Verify that it is expected
        if (func_args_header_t::match_function(_request.header, _response.header)) {
            if (_response.header.func_args_size) {
                _response.data.resize(_response.header.func_args_size);

                // Wait for response data
                boost::asio::async_read(_socket,
                    boost::asio::buffer(
                        &(*_response.data.begin()), _response.data.size()),
                    boost::bind(&rpc_client::_handle_response_data,
                        this,
                        boost::asio::placeholders::error,
                        boost::asio::placeholders::bytes_transferred,
                        _response.data.size()));
            } else {
                _handle_response_data(err, 0, 0);
            }
        } else {
            // Unexpected response. Ignore it.
            UHD_LOGGER_DEBUG("NIRIO") << "rpc_client received garbage responses.";
            _exec_err.assign(boost::asio::error::operation_aborted,
                boost::asio::error::get_system_category());

            _wait_for_next_response_header();
        }
    }

    if (_exec_err)
        _exec_gate.notify_all();
}

void rpc_client::_handle_response_data(
    const boost::system::error_code& err, size_t transferred, size_t expected)
{
    std::lock_guard<std::mutex> lock(_mutex);
    _exec_err = err;
    if (transferred != expected) {
        _exec_err.assign(boost::asio::error::operation_aborted,
            boost::asio::error::get_system_category());
    }

    _exec_gate.notify_all();

    _wait_for_next_response_header();
}

void rpc_client::_wait_for_next_response_header()
{
    //_mutex must be locked when this call is made
    boost::asio::async_read(_socket,
        boost::asio::buffer(&_response.header, sizeof(_response.header)),
        boost::bind(&rpc_client::_handle_response_hdr,
            this,
            boost::asio::placeholders::error,
            boost::asio::placeholders::bytes_transferred,
            sizeof(_response.header)));
}

}} // namespace uhd::usrprio_rpc
